I was hoping someone could expand a bit on the role of marine clocks in gaining the naval upper hand during the age of colonialism. I remember reading some basic info about how oceanic navigation had often before been based on travelling along a specific line of latitude, giving navies predictable places to wait for an enemy, but the longitudinal clock freed navies from this constraint, but I haven't been able to find much information on that. H4, the quintessential timepiece by Harrison wasn't finished till the 1760s, and that the French were close on his heels.
How much of an edge did this give the British at first, and how long till they were adopted in other navies (or in colonial company/merchant ships)? Was it the jumpstart that the chronometer gave them that let the Brits gain naval dominance, or was the technology rapidly disseminated amongst all the colonial powers and allow for expansion of already significant colonial claims without major changes in the balance of power?
I wrote about this in a previous answer. The "money quote" is
The idea that the chronometer led to a revolution in navigation is one of the most overblown ideas about science I can think of.
To quote myself again,
Chronometers were only provided to British naval ships traveling in far distant waters starting in the 1790s, and did not become standard issue until the 1840s. (Captains or masters could buy chronometers, although they were horribly expensive -- 60 to 100 guineas new, plus 5 or 10 per year for cleaning/resetting, and ships needed three to correct for errors.)
New methods for finding longitude were important in all navies being better able to navigate, but the chronometer was only one of them. "Lunars," finding the position of heavenly bodies (our moon, the moons of Jupiter, etc.) in relation to other places also helped people find latitude.
And it's worth pointing out that none of these discoveries made any difference without accurate charts. It's not like navigators said "by Jove now I can take my satellite-based Mercator projection an put my ship exactly upon it!"
There are a lot of reasons for British naval superiority in the 18th century and later, including proficiency in navigation. The chronometer is important, but not the only one, by any means.
Edit: I realize my response may have come off as a bit acerbic. I think it's because the formulation of "this specific technology = win for my team" is really something that irks me. It's the worst kind of techno-nonsense, and I blame Civilization and games like it for instilling this notion in people's minds: you tech to Chronometer and all of a sudden you have battleships up against enemy triremes. In fact, the British navy achieved its hegemony by a long process of training and institutional knowledge to make its officers, and sailors, the best in the world. Part of that was skill at navigation, but part of this was also the entire process of learning how to command a ship -- which navigation was a part of, and chronometers a part of that.